[From gene to disease; from CLN1, CLN2 and CLN3 to neuronal ceroid lipofuscinosis]

The neuronal ceroid lipofuscinoses (NCL) are worldwide the most common lysosomal storage disorders of childhood. Clinical features often include progressive visual impairment, seizures, psychomotor deterioration, dementia, and premature death. Most NCL cases are caused by mutations in the CLN1, CLN2 and CLN3 genes, which play an essential role in lysosomal protein degradation. Laboratory diagnostics for a patient suspected of NCL should start with enzyme analysis in the case of INCL and LINCL and investigation of lymphocyte vacuolisation for JNCL. Diagnosis at the protein level is not available for JNCL, but CLN3 mutation analysis is possible. The carrier status of healthy relatives in families with known mutations in either CLN1, CLN2, CLN3 or CLN6 can be determined with certainty by mutation analysis.